How many 4 bit paraller adders will be used in 2 digit bcd adder?

A 2-digit BCD (Binary-Coded Decimal) adder requires two 4-bit parallel adders, one for each digit. Each BCD digit can represent values from 0 to 9, which can be expressed in 4 bits. When adding two BCD digits, these 4-bit adders compute the sum, and if the result exceeds 9, an additional adjustment may be needed, but this does not require extra adders. Therefore, the total is two 4-bit parallel adders for a 2-digit BCD adder.